top button
Flag Notify
    Connect to us
      Facebook Login
      Site Registration

Facebook Login
Site Registration

Does SI request RACH happens using contention free or contention based in NR?

+1 vote
Does SI request RACH happens using contention free or contention based in NR?
posted Mar 7, 2018 by Jaganathan

Share this question
Facebook Share Button Twitter Share Button LinkedIn Share Button

2 Answers

+1 vote

As I know, In the contention-free mode, the eNB can uniquely identify the UE by a received preamble sequence, due to the fact
that the preamble to be used has been communicated to the UE in advance. Such a scenario is possible in certain cases,
e.g., during a handover between two eNBs.
In on demand SI request RACH, RACH-ConfigDedicated mode used & it is used for handover to the cell. So I think in this case contention-free RA procedure will use.
Waiting for other expert comment !!

answer Mar 7, 2018 by Mohit Mohan
0 votes

►The Random Access Procedure is used for four cases:
• Initial access from disconnected state (RRC_IDLE)
• Handover requiring random access procedure
• DL or UL data arrival during RRC_CONNECTED after UL PHY has
lost synchronization (possibly due to power save operation)
• UL data arrival when are no dedicated scheduling request channels
►There are two forms of the Random Access Procedure
• Contention based (applicable to all four events)
• Non-contention based (applicable to only handover and DL data

answer Jan 30, 2020 by Thierry Bodog
Similar Questions
0 votes

Handover RACH will be initiated as Contention free, RNTI will be included in Mobility info. But while doing RACH What will be the RNTI value included in RAR? Will this be same as Mobility RNTI?

0 votes

weather it is RRCConnection request or direct NAS message as ULInfotransfer?

+1 vote

If HO fails the UE will initiate contention based reestablishment and connect to some ENB, But target ENB have provided the contention free Rach preamble , at failure case how long ENB will hold this preamble because it has to release for other UE?

Contact Us
+91 9880187415
#280, 3rd floor, 5th Main
6th Sector, HSR Layout
Karnataka INDIA.